Envisioning the many potential benefits of virtualization — simplified IT management, optimized resource utilization, and reduced energy costs, among others — it's no wonder that organizations are stepping up their efforts to transform physical IT infrastructures into virtual ones. As they do so, the impact of virtualization on network I/O is a top-of-mind consideration. Increases in platform performance, multi-core processing, hardware resource utilization, I/O speed and the number and density of virtual machines (VM) all contribute to a corresponding rise in the volume and complexity of I/O traffic.

I/O bottlenecks are particularly troublesome because they impair application performance and limit the number of VMs deployed. One method that helps reduce bottlenecks and improve system performance involves giving VMs direct access to hardware I/O devices. This approach avoids the overhead of embedded software switches.

Server and interconnect vendors are driving next-generation server I/O virtualization with NIC partitioning. NIC partitioning is a method of dividing a single physical Ethernet port into four partitions, or virtual ports, which enables administrators to conserve PCI Express (PCIe) slots in the physical host server. In addition, NIC partitioning allows administrators to dedicate bandwidth for VMs and associated applications and to apply QoS to the virtual ports, helping improve I/O performance. NIC partitioning does not require special OS or hypervisor support, so it can be incorporated in existing IT infrastructures.

Easing the transition to 10 Gigabit Ethernet

NIC partitioning helps manage the transition to 10 Gigabit Ethernet (10G) networking by eliminating the need to deploy multiple dedicated Gigabit Ethernet ports for different traffic types in a single physical server. Instead, they can replace multiple gigabit Ethernet ports with fewer 10G ports while still maintaining the high performance, bandwidth provisioning flexibility, and isolation attributes found in the physical server environments.

NIC partitioning paves the way to a smooth 10G Ethernet migration by enabling administrators to divide a single 10G Ethernet adapter into multiple independent partitions. Each partition is designed to support concurrent storage and data networking protocols, including TCP/IP, Fibre Channel over Ethernet (FCoE), and iSCSI. As a result, this approach minimizes deployment disruptions and avoids OS changes to implement flexible bandwidth provisioning to applications running in the VMs.

In addition, flexible provisioning and multiple partitions help lower adapter, cabling, switch port, and management costs. Because NIC partitioning is agnostic to the external Ethernet switch, it avoids the related dependencies to regulate and manage bandwidth. Consequently, administrators are free to use an Ethernet switch of their choice.

For certain configurations, NIC partitioning also enables the switching of VM-to-VM traffic within the physical server through a Layer 2 switch embedded in the adapter. By offloading VM I/O from the host server, NIC partitioning helps free the processor to run additional applications.

Implementing NIC partitioning in a virtualized OS environment administrators can implement it in either a native (bare metal) or a virtualized OS environment. Consider an example use case for a virtualized platform running on a blade server. Data centers today typically deploy multiple Gigabit Ethernet NICs to isolate and regulate different traffic types being generated by the various applications residing on a single blade server: one NIC dedicated to OS kernel traffic, one NIC to management traffic, one NIC to backup traffic, and yet another NIC for the storage interface.

However, using multiple Gigabit Ethernet NICs can lead to high management and infrastructure costs because each NIC adds to the management complexity and the amount of adapters, cables, switch ports, power, and cooling required. Moreover, the number of available I/O expansion slots limits the number of dedicated GbE ports in a blade server that an administrator can deploy. And finally, administrators cannot run applications that need more than GbE bandwidth because they are limited by the fixed Gigabit Ethernet bandwidth.

As an alternative, administrators can install a converged network adapter (CNA) mezzanine card in the blade server. This NIC partitioning-enabled network adapter consolidates dedicated GbE ports into partitions of a single 10G Ethernet port, thereby enabling cable consolidation. From an OS perspective, no changes are required, which facilitates a smooth deployment. The eight partitions supported by the dual-port adapter appear as eight independent, discrete NICs to the OS.

Administrators can set maximum and minimum bandwidth and implement dynamic bandwidth balancing for NIC partitioning, which enables applications to get the appropriate bandwidth when they need it. This flexibility is available without installing a different external Ethernet switch infrastructure, because NIC partitioning is switch-agnostic. (See High-speed Ethernet planning guide.)

Because NIC partitioning enables hardware consolidation and does not require a proprietary switch infrastructure, the technology, coupled with blade servers, helps organizations lower total cost of ownership for deploying cloud computing and virtualized environments. And by enabling organizations to transition from Fibre Channel to FCoE or iSCSI over 10G Ethernet, NIC partitioning facilitates the deployment of cost-efficient, flexible network.

Coon is a product marketing manager within Dell's QLogic Host Solutions Group, Gupta is a senior product marketing manager at Dell focused on server I/O and networking technologies, and Deshmukh is a senior technical marketing manager at Dell specializing in server peripheral devices.

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